[metapost] a problem of label when using metapost

[source liu]

On Tue, Nov 22, 2011 at 3:20 AM, Dan Luecking <luecking at uark.edu> wrote:
> At 10:54 PM 11/21/2011, you wrote:
>>
>> Hi,all
>>
>>  I've recently figure out something,
>>  I sometimes include the package {amsmath} here
>> as
>> ====================
>>     verbatimtex
>>     \documentclass{article}
>>     \usepackage{amsmath}
>>     \begin{document}
>>     etex
>> *some metapost here*
>>
>> verbatimtex
>> \end{document}
>> etex
>> ====================
>>
>> I find the latex alway give "failed to generate *mpx" file,
>> ---> tex --parse-first-line --interaction=nostopmode mp030238.tex
>> and it gave an error indicate at after btex
>
> Do you have the amsmath package?

Yes, I do, I would like to include them at the very beginning of my
document, for i
sometimes want to type some math,  of course, at first thought i
included amsmath
package when i use metapost to draw some axises, unconsciously .

>
> Examine the files that remain if you run mpost with option
> --debug. In cases where the tex label production fails, the
> relevent files are mpxerr.tex and mpxerr.log. (At least they
> are named that in my version of metapost: 1.506.) When the
> label making succeeds, the files have some random names
> beginning with "mpa".

The error says nothing about amsmath package, but the fact is, to
exclude the package,
It does works.


> By the way, modern metapost should invoke etex. That is, my errors
> look like the following (but all on one line):
>  makempx fatal: ./mth4.mp:
>  Command failed:
>  etex --parse-first-line --interaction=nonstopmode mpa00408.tex;

yes,  something like that,  but i'm not sure for now whether is etex
or tex of mine.

and there is a line break after btex
something like
label.bot(btex           %here
        *sometex *  etex , "z0")

then goes the error like you mentioned above.




-- 
Liu An
Institution of modern physics, Shanghai, China